New recipe and visitor to change the access level of a java method

[murdos]

Fixes #622

[murdos]

These are tests / situations that are currently not correctly handled.
Some (all?) are already not supported by code in existing visitors (see links in the ticket + changes in HideUtilityClassConstructorVisitor).
I spent quite some time on it, but I haven't succeed in fixing them (this is my first incursion with AST ^^)

I think this PR is already an improvement, in the sense that it'll factorize the logic, and that all other visitors using it will benefit from improvements and future fix to this visitor.

[jkschneider]

Thank you so much for all the hard work on this @murdos! I made some further edits to support more use cases, so there is only one test still disabled now on main. And we can continue working from main. This PR is merged with a series of commits on main ending with 52f7c10.

Please check it over and see if I've correctly incorporated everything you added in the past couple days.

[github-actions]

Unit Test Results

   431 files  ±0     431 suites  ±0   3m 44s ⏱️ ±0s
2 112 tests ±0  2 078 ✔️ ±0  34 💤 ±0  0 ❌ ±0 
3 005 runs  ±0  2 959 ✔️ ±0  46 💤 ±0  0 ❌ ±0 

Results for commit 52f7c10. ± Comparison against base commit 52f7c10.

[murdos]

Please check it over and see if I've correctly incorporated everything you added in the past couple days.

Thanks for polishing and having merged my work!
It seems that there are some divergences, mainly on tests, but nothing important. Your final version looks fine.